Facebook’s Plans for Space Lasers Revealed - IEEE Spectrum
▻https://spectrum.ieee.org/tech-talk/aerospace/satellites/facebooks-secret-space-lasers
PointView is the company that IEEE Spectrum revealed last year to be a previously unknown subsidiary of Facebook working on an experimental satellite called Athena. In April, PointView sought permission from the U.S. Federal Communications Commission to test whether E-band radio signals could “be used for the provision of fixed and mobile broadband access in unserved and underserved areas.”
That application was still pending at the FCC before the current U.S. federal government shutdown took effect, but it and other public documents and presentations now strongly suggest that PointView is planning to utilize laser technology, possibly both in Athena and future spacecraft.
Facebook has long been interested in free space optical, or laser, communication technology. Lasers are able to support much higher data rates than radio transmitters for a given input power, and their signals are largely immune to interference or hacking, although clouds can be problematic.
Although Facebook developed millimeter-wave E-band links for its stratospheric Aquila drones, it was also experimenting with air-to-ground laser communications before it canceled its drone program last June. The laser tests, which used technology supplied by German company Mynaric, succeeded in establishing 10-gigabit-per-second links between a ground station and a light aircraft flying overhead.
“We proved that a link could be re-established near instantaneously without any discernible downside,” Paul Cornwall, a Mynaric spokesperson, told Spectrum. “That’s pretty key for people looking to establish [high altitude or satellite] constellations.” However, the company would neither confirm nor deny that it was still working with Facebook.
Perhaps coincidentally, PointView’s application for its Athena satellite contains confidential redacted sections that PointView claimed “specifically concern the use and implementation of technologies that are not regulated by the [FCC]… [and]… information controlled by the Export Control Regulations.” A laser tracking system would fulfill both requirements.
The geostationary setup Aniceto describes would differ considerably from the laser system Facebook tested with Mynaric. On the plus side, using a geostationary satellite would mean that ground-based observatories would not need to track rapidly moving objects, such as drones or satellites in low Earth orbit. However, even tightly focused laser signals would spread out and become weaker on the long 36,000-kilometer journey from a geosynchronous orbit.
“The light from an optical beam… would actually spread to encompass a fraction of a city,” said Aniceto. “[And] if the satellite and the laser communication were off pointing this beam by even just one degree, it would completely miss the planet.”
Although the system Aniceto described may differ from the one Facebook is developing, she concluded her speech by saying: “Join me as I continue to develop new technology or as I find alternative ways to use existing technology to make the greater impact of connecting the unconnected.”
Zac Manchester, an assistant professor of Aeronautics and Astronautics at Stanford University, told Spectrum that he has no knowledge of any Facebook satellites but is aware that the company has been working on laser communications. “I’ve seen some of their work in the area,” he said. “It’s very cool.”
#Facebook #Satellites #Orbite_géotationnaire #Communication_laser